OBJECTIVE:
To describe sociodemographic characteristics and analyze temporal trends in
the mortality of motorcyclists injured in traffic accidents.METHODS: This was a time-series study with data from 580 motorcyclist
deaths in the Brazilian Federal District from 1996 to 2007. The data were obtained
from the Mortality Information System. Mortality rates specific for age and
sex, the standardized rates (direct method), and the ratio of deaths per fleet
(motorcycles) were calculated. The centralized moving average of the standardized
mortality rate for men was calculated for a three-year period, and a linear
regression model was constructed to study the evolution of mortality. The joinpoint
method (inflection point) was used to calculate the annual increase in the standardized
mortality rate.RESULTS: Most of the motorcyclists killed were male (94.3%), mixed skin
color (71.0%), and between the ages of 20 and 39 years (73.8%). The standardized
mortality rate for resident motorcyclists (men) was 1.9 to 7.2 deaths/100,000
men between 1996 and 2007. Between 1998 and 2007, the ratio of deaths per fleet
increased from 2.0 deaths/10,000 motorcyclists to 10.0 deaths/10,000 motorcyclists
among men. There was an estimated annual increase of 0.48 deaths/100,000 men
(95%CI 0.31, 0.65; p <0.001). The percent increase of the annual standardized
mortality rate for males was 36.2% in the period from 1998-2007 (95%CI 21.2%,
53.2%; p <0.05).CONCLUSIONS: The mortality rate resulting from motorcycle road accidents
has increased dramatically. This increase is partially explained by the increase
of the fleet of motorcycles. Individual characteristics of drivers, as well
as local traffic conditions, need to be investigated for the planning of preventive
policies.

Road traffic accidents
(RTAs) are a serious public health problem worldwide, as they are responsible
for a large number of cases of mortality and temporary and permanent disabilities.
The World Health Organization (WHO) estimates that 1.2 million deaths result
from RTAs each year, and there are even higher numbers of nonfatal and disabled
victims, especially in emerging countries.ª
The WHO estimates a 40% increase in mortality worldwide for these groups by
2030 if no effective preventive measures are adopted.b
Approximately 62% of deaths from RTAs occur in ten countries, and Brazil ranks
fifth in terms of the number of deaths.c

According to data
from the Death Information System (Sistema de Informação sobre
Mortalidade, SIM) from the Brazilian Ministry of Health, RTAs caused the
deaths of 37,407 people in Brazil in 2007 (3.6% of the total deaths). That same
year, 8,078 motorcyclists injured in traffic accidents died (21.6% of the total
deaths from RTAs), an average of 22 deaths per day. This exceeded the proportion
of deaths of car occupants (21.3%).d

Several Brazilian
studies indicate that mortality from RTAs is higher among men, particularly
young men (over 50% of deaths occur between the ages of 15 and 44),7,12,22
and the proportion of motorcyclists among these victims is significant, ranging
from 30% to 50%.4,5,14

Among the major
policies related to the prevention of RTAs, the Brazilian Traffic Code (Código
de Trânsito Brasileiro, CTB) Law No. 9503 was passed in 1998. The
CTB has promoted the decentralization of traffic enforcement and set strict
rules regarding speed limits and the mandatory use of safety equipment such
as seatbelts and helmets. It also raised the value of traffic fines; created
a rigorous system of scoring for traffic infractions, which can lead to the
loss of one's driver's license; and set higher requirements for licensing drivers
and for licensing vehicles.7

Despite the reduction
in overall mortality from RTAs (from 11.4 deaths/100,000 men aged 20 to 49 years
old) in the post-implementation period of the CTB,7 the number of
accidents involving motorcyclists has increased between 1980 and 2003, especially
since 1995.22 Since 1998, the death rate of motorcyclists injured
in traffic accidents has continued to increase in all regions of the country,
especially in cities with smaller populations.e

In Brazil, until
the 1980s, the motorcycle was used for leisure. In subsequent years, it gained
acceptance as a fast, economical, low-cost vehicle.f
The fleet of motorcycles increased 300% from 1998 to 2007.g
Gradually, the motorcycle has become an important option for individual transport
and a working tool for motorcycle-freighters and mototaxis, particularly in
Asian countries including Laos, Indonesia, Cambodia, and Thailand, which account
for more than 70% of the fleet of vehicles.h

With the increase
of the fleet and the increasing use of motorcycles in the labor market, the
occurrence likelihood of accidents involving motorcyclists is increased by other
drivers' difficulty in visualizing the motorcycle, dangerous traffic behavior,
and disregard for traffic laws. Article 56 of the CTB, which prohibited motorcycle
traffic between lanes, was vetoed, despite the fact that moving between the
rows of cars increases the risk of accidents involving motorcyclists.23
In Brazil, few cities have exclusive lanes for motorcyclists.

The victims of
traffic accidents are likely to suffer serious injuries in the head and extremities
(upper and lower limbs), often have long periods of hospitalizations with serious
sequelae, and sometimes the occurrence of fatal injuries.1,3,16,17
The increased severity of accidents is related to the large body of exposure
in motorcyclists and to the negligence of the use of safety equipment.2,16
Studies of motorcyclists involved in traffic accidents show that higher proportions
of fatalities occur among motorcycle drivers (45.2 to 83.6%) compared to passengers.8,14,15,21

The Brazilian Federal
District (FD) has the highest proportion of cars per inhabitants in the country
(one vehicle per 2.5 inhabitants), yet it is only smaller than the state of
Santa Catarina, Southern Brazil (one vehicle per 2.3 inhabitants). The FD had
89,960 motorcycles in 2007, representing 9.2% of the total fleet, a ratio of
8.3 cars per motorcycle. In Brazil, in the same year, the proportion of motorcycles
in relation to the total fleet was 22.5%. Although the FD displays one of the
highest proportions of vehicles per inhabitants in the country, the ratio between
motorcycles and inhabitants is 27 per 1,000 inhabitants. This is lower than
that observed in the country overall, which is 43 motorcycles per 1,000 inhabitants.i
According to data from the Federal District Department of Transportation, 159,456
drivers were qualified to ride motorcycles in 2005, which corresponded to 14.9%
of all drivers qualified in the FD.j

Despite the low
motorization of motorcycles in the FD, motorcyclists are vulnerable and often
compete with a significant number of vehicles. There has also been a general
increase in fleets in recent years. Nonetheless, there has been a lack of studies
about this region. Therefore, the purpose of this study was to characterize
the motorcyclists killed in traffic accidents and analyze the temporal trends
in mortality.

METHODS

We conducted an
exploratory time-series study about mortality of motorcyclists injured in traffic
accidents in the Distrito Federal from 1996 to 2007. Data were collected from
theSIM. We selected the deaths of motorcyclists (drivers and/or passengers)
who were victims of transport accidents (codesV20-V29 of the 10th
revision of International Classification of Diseases - ICD-10).

In the descriptive
analysis, the deaths in the FD were characterized by the date and place of occurrence,
and victims were characterized by gender, age, marital status, schooling, skin
color, condition at the time of the accident (driver or passenger), type of
accident, and place of residence (resident or non-resident of the FD).

In the time-series
analysis, only the deaths of residents of the FD were considered. Population
data, estimated by the Instituto Brasileiro de Geografia e Estatística
(Brazilian Institute of Geography and Statistics, IBGE), were used to calculate
the specific rates of annual mortality (stratified by gender and age) and the
standardized mortality rates (by gender and age) by the direct method (standard
population: Brazil, 2000). Given the small proportion of deaths in women, we
chose to present only the death rates for males. Data on the entire fleet of
motorcycles from the National Traffic Department (Denatran) were used to calculate
the ratio of deaths per fleet (deaths per 10 thousand motorcycles) in Brazil
and in FD for the years from 1998 to 2007. To explain the observed annual changes
in mortality rates, we examined the Pearson correlation coefficient between
the variables "year" and "fleet of motorcycles."

We calculated the
centralized moving average of the three-year period standardized mortality rate
in men. Then, a linear regression model was constructed with the moving average
of the standardized mortality rate as the dependent variable and "year" as the
independent variable. To avoid colinearity, the variable "year" was centered
from 2001 (midpoint of the series).

To calculate the
annual increase in the standardized mortality rate, we used the joinpoint method
(inflection point). This allows the adjustment of a series of data from the
fewest possible joinpoints (zero, i.e., a line without points of inflection),
and it also tests whether the inclusion of more joinpoints is statistically
significant.10 The significance tests used are based on the permutation
method of Monte Carlo and on calculation of the annual percentage change in
the standardized mortality rate, which used the logarithm of the rate.

Statistical analysis
was performed using Stata (version 9.0), SPSS (version 15.0) and the Joinpoint
Regression Program (version 3.4.2). Statistical significance was set at p <0.05.

The study was approved
by the Ethics Committee of the School of Medical Sciences of Santa Casa de São
Paulo (Report 067/09).

RESULTS

Between 1996 and
2007, there were 7,345 deaths of RTA victims in the FD, with 580 being motorcyclists
(7.9%), 392 deaths from accidents without further specification, and 416 deaths
from vehicle accidents of unspecified type. The number of deaths of motorcyclists
increased from 25 in 1996 to 139 in 2007. The distribution of deaths over the
year ranged from 5.5% in February to 11.2% in October. Sunday was the day of
the week with the largest proportion of deaths (17.4%), followed by Tuesday
(16.9%). In addition, 427 (73.6%) deaths occurred in hospitals (Table
1). The proportion of deaths on public roads increased from 14.7% in 2000-2003
to 29.8% during 2004-2007.

Most victims were
male (94.3%), mixed skin color (71.0%), single (68.1%), aged between 20 and
39 years (73.8%), and schooling from 4 to 11 years (54.8%) (Table
2). A large number of deaths occurred in non-resident individuals (201 deaths,
34.7%). Schooling was ignored or unavailable for 17.1% of the victims, although
an increase in the completion of formal education has occurred over the years.
The skin color of victims in approximately 6% of deaths was not recorded. For
the variable "occupation", the proportion of missing data reached 31%, which
made this analysis impractical.

The most frequent
type of RTA involving motorcyclists was collision with another vehicle (car,
truck or van, 39.7%), followed by accidents without collision (35.7%). Drivers
accounted for 67.8% of deaths, followed by 29.7% in the unidentified condition.
There were 22 reported deaths in individuals under the age of 18, of which 14
(63.6%) were drivers (data not shown in Table).

In the majority
of the years analyzed, higher specific mortality rates were observed in males
in the group aged between 20 and 29 years (Figure
1). This age group also had the largest increase (184.9%) in mortality rate.
In 2007, the risk of death from RTA in a male motorcyclist aged 20 to 29 was
15.2 times that of a 19-year-old man, 3.3 times greater than that of a man of
50 years or more, and 1.6 times greater than that of a man 30 to 49 years.

The standardized
mortality rate for male motorcyclists injured in RTAs increased from 1.9 deaths
per 100,000 men in 1996 to 7.2 deaths per 100,000 men in 2007. The ratio of
male deaths per fleet of motorcycles increased from 2 per 10,000 (1998) to 10
per 10,000 (2007) (Figure 2).

From the linear
regression model, there was an estimated annual increase of 0.48 deaths/100,000
men in the standardized mortality rate (CI 95% 0.31, 0.65; p <0.001). The
coefficient of determination of the line obtained was high (R² adjusted
= 0.83), suggesting that the variable "year" explains an important part of the
observed variation in the standardized mortality rate. The variables "year"
and "fleet of motorcycles" were strongly correlated (r = 0.99).

The percent increase
in the standardized mortality rate for males was 36.2% in the period 1998-2007
(CI 95% 21.2%, 53.2%; p <0.05) (Figure 3).

DISCUSSION

Between 1996 and
2007, there were 7,345 deaths in RTA victims in the FD, of which 580 were motorcyclists
(7.9%). In 2007, the deaths of motorcyclists accounted for 22.2% of deaths,
and the death ratio (males) per fleet was 10.0 deaths per 10,000 motorcycles,
almost five times the number of fatal crashes involving cars (2.2 deaths for
every 10,000 cars). About 95% of motorcyclists who died as a result of RTAs
were male, similarly to results in other national studies, in which the proportion
of men was higher than 80%.1,5,18 The largest proportion of deaths
among men aged 20 to 29 years is consistent with other studies on mortality
by RTAs using secondary data22 and studies conducted in emergency
services.4,6,14,15

Over 65% of motorcyclists
who died as a result of RTAs were single, as noted by other authors.17,25
Veronese et al25 raised the hypothesis that, in some cases, the prevalence
of mortality among singles is due to a lack of commitment to a family, which
would make motorcyclists take greater risks in traffic, by causing or suffering
accidents.

Nearly half of
motorcyclists injured between 2004 and 2007 had eight or more years of schooling,
following the pattern of two studies conducted in São Paulo, Southeastern
Brazil, where 35.04 and 53.9%9 of motorcyclists treated
in the emergency services had completed high school.4,9 Similarly
to other national and international studies, motorcyclists had a higher death
rate than passengers.1,8,14,21

Among the 580 deaths,
22 (3.8%) were individuals under 18 years of age. Of those under age 18, 63.6%
were drivers, although they had no driver's license. Studies suggest that the
proportion of motorcycle riders under the age of 18 years may be greater than
30%,1 and some authors associate driving such vehicles before the
allowed age with the issue of transgression during adolescence.16
The mortality of a teen driver is a complex phenomenon, which could partially
be explained by the inherent characteristics of this group, such as immaturity,
feelings of omnipotence, a tendency to overestimate their skills, little experience,
limited ability to drive, and risky behaviors.13

The predominant
deaths of motorcyclists of mixed skin color (75.6%) contrasts with the distribution
of the local population by skin color. According to the 2000 Census, only 44.8%
of men reported to be mixed.k
In Brazil, the mortality rates of white and brown male motorcyclists were, respectively,
4.3 and 4.0 deaths/100,000 inhabitants in 2003.The comparison of mortality rates
of white and brown males based on schooling showed highest risk of death for
motorcyclists with four or more years of schooling for both categories of skin
color.l

Over 70% of deaths
in motorcyclists in the FD occurred in hospitals. In contrast to this finding,
a study conducted in India showed that 42.8% of the deaths occurred before the
victim arrived at the hospital.8 Despite the severity of the injuries
generally suffered by motorcyclists,11 it is possible that the availability
of emergency and pre-hospital services in the FD explains the lower proportion
of deaths on public roads. DATASUS data indicate that the average duration of
hospitalization of motorcyclist RTA victims was 10.7 days between 1998 and 2007,
and 24.1% of the hospitalized victims died before completing 12 hours of hospitalization.

The finding of
a higher proportion of deaths on Sundays is difficult to explain because the
majority of motorcyclists died in hospitals. It is impossible to determine whether
this finding reflects the higher concentration of accidents that day or if accidents
that occurred on other days of the week caused the hospitalization of the victims
who later died. Studies analyzing RTA victims treated at emergency services
in Teresina (PI, Northern Brazil) and Maringá (PR, Southern) in 2006
and 1999, respectively, showed that the highest number of RTAs involving motorcycles
occurred on Fridays and Saturdays.8,14 Other studies in Maringá
(PR)m and Londrina (PR, Southern
Brazil) in 2004 and 2005, , showed Sunday as the day of the week with the highest
number of RTAs involving motorcyclists.19,20 The lowest proportion
of deaths was observed in February (5.5%). An association between the number
of deaths of motorcyclists and times of the year has not been observed in the
literature.

Because the data
described in this study refer to the date and place of death (and not the accident),
it was impossible to explore the distribution of accidents over the periods
of the day. Liberatti et al13 found a higher concentration (39.6%)
of fatal crashes at night (6:00 to 11:59 pm). It is possible that the higher
incidence of fatal accidents at night is a consequence of reduced visibility,
fatigue at the end of the day, and higher consumption of alcoholic beverages.
Some authors suggest that among professional drivers, the excessively long workday
- up to 15 hours without interruption - may be one of the factors associated
with the higher incidence of accidents in the night period.19

Collisions of motorcycles
with cars or trucks were responsible for a significant proportion of deaths
(35.9%) in this study. This type of accident can be a consequence of the difficulty
of other drivers in seeing the approaching motorcycle and avoiding the collision
and the unpredictable movement of motorcyclists between the rows of cars in
motion,1,3,23,24 among other factors.

The highest mortality
rate in this study was registered for men aged 20 to 29 years (17.4 deaths/100,000
in 2007). Andrade & Mello-Jorge,1 in a study conducted in Londrina
in 1996, found specific mortality rates for young riders higher than those observed
in the DF (37.0 deaths per 100,000 inhabitants).

The risk of death
of motorcyclists injured in RTAs greatly increased in the FD (36.2% per year),
which may be linked to several factors. The increased number of motorcycles,
and therefore, motorcyclists, result in a higher number of individuals susceptible
to accidents and the increase in the absolute number of deaths from this cause.

Regarding public
policies on transportation, the federal government granted tax concessions and
other benefits for the purchase of motorcycles in the 1990s. This was done under
the guise of the creation of jobs and allowing low-income youth to have access
to a means of motorized transport, thereby raising the number of motorcycles
in circulation in the country. However, the structure of the traffic routes
was not adequately prepared, and there were no effective inspection actions.23
The poor conditions of roads, signaling, average velocity of flow, drainage,
and lighting also increase the risk of accidents involving motorcyclists.

The precarious
work conditions for professional motorcyclists are another determinant for the
increased risk of accidents. In general, these motorcyclists perform services
for which they are paid according to their productivity, which would exacerbate
the quest for speed at the expense of respect for traffic laws and the practice
of defensive driving.1,3,19,23,24 Interestingly, the same society
that uses (and appreciates) the services of professional motorcyclists, requiring
them to be as quick as possible, consider them to be dangerous individuals in
traffic.

Studies that correlate
death certificates with police reports would allow a better understanding of
traffic accidents involving motorcyclists and the conditions that lead to these
deaths. Thus, it would be possible to establish the relevance of factors such
as maintenance of motorcycles, use of helmets and other safety equipment, the
behavior of motorcyclists in traffic, and the severity of injuries experienced
by motorcyclists in accidents.

The interpretation
of results must include consideration of limiting factors related to the quality
of data on mortality, especially concerning flaws in the completeness and validity
of the records. For example, in 2007, among the 626 deaths due to accidents
in the FD, 3.5% were caused by RTAs without specification of the vehicle or
victim. Additionally, no information was available regarding the condition of
the driver or passenger at the time of the accident in 29.7% of motorcyclists
killed in RTAs. Moreover, in the period from 1996 to 2007 in the FD, there were
416 deaths classified as being caused by accidents "with a motor or non-motorized
vehicle, type of vehicle unspecified" (V89) and 392 as a result of "accident
without any specification" (X59). While the number of deaths coded as "unspecified
vehicle accident" was reduced from 231 in the years from 1996 to 1999 to 50
between 2004 and 2007 and the number of deaths by "accident not otherwise specified"
was reduced from 178 to 105, the deaths of injured motorcyclists increased from
71 to 366. Thus, it is possible that a proportion of deaths of motorcyclists
injured in accidents has not been accounted for, especially at the expense of
errors in classifying the type of accident, as is described in the literature.2
Improving the quality of information on the cause of death is one possible explanation
for the small number of deaths of motorcyclists in the early years of the series
and for its great growth in subsequent years. Moreover, in general, the DIS
in the FD has been enhanced significantly and has high coverage rates (90%)
and low proportions of ill-defined deaths. The proportion of ill-defined deaths
(Chapter XVIII of CID 10), which already had low values in 2000 (4.7%), declined
even more, reaching 2.4% of total deaths in 2007. Another limitation of this
study was the impossibility of knowing whether the victim was or was not working
when the accident occurred, which does not allow more detailed investigations
of the deaths of professional motorcyclists.

In conclusion,
this study highlights the increased mortality of motorcyclists by RTAs in the
DF, especially among young men. However, the deaths represent only a small portion
of the total number of motorcyclist victims of RTAs. Thus, further studies are
needed to provide more detailed evidence about the risk of accidents and deaths
in motorcyclists. These are issues of great relevance to public health.